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I wasted the whole day on a damn KMC chain.....

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I wasted the whole day on a damn KMC chain.....

Old 04-19-12, 01:47 PM
  #101  
ColinL
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Originally Posted by coolmingli View Post


I just took one picture in the front of the rear derailleur, then one from the side, it is the camera angle, the chain is fine.

According to park tool, an Adequate chain length should be like the picture below.


step back a second.

I realize the park tool blog is a good resource, but you really need to look at shimano's documents. you have a shimano drivetrain.
assuming it's 7800-- but it shouldn't matter: http://techdocs.shimano.com/media/te...9830612494.pdf
note how shimano shows two methods for sizing the chain... big/big plus 2 links, or big/small and align the pulleys.

I don't know what the hell that park tool picture is of, but your chain is too short and if you ride it like that you're eventually going to kill the derailleur or the hanger, and when it goes into your spokes it won't be a happy event. I don't know why you managed to get it working with the shimano chain, but this isn't a kmc issue. it's a too short chain issue.
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Old 04-19-12, 02:38 PM
  #102  
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well. I'm with Boyd, BDop and the others... Shimano's website says a compact 50/34 with 11-28 is compatible with dura-ace rd... but I use 106 links (counting the rollers not the inside links... inside links would be 53) with compact and 11-25 cassette. THAT shifts perfectly, and leaves the RD looking less tortured. I would say that 108 rollers (54 inside links) would be appropriate for the 11-28 and should still work in 34-11 if the B screw was properly tensioned. I will take your x10sl chain and test it on my 6750 drive train and let you know if it works though...
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Old 04-19-12, 03:13 PM
  #103  
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Currently running 9-speed KMC chains with both Shimano and SRAM cassettes, Campy and Shimano shifters. Zero problems.

Looking at the photos, the chain length looks suspect. What does it look like when you shift onto the big ring and small cog?
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Old 04-20-12, 02:53 AM
  #104  
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108 links are too long for all 3 chains, the chain will touch the rear derailleur at the 2 smallest cogs(B tension in), I will take my bike to the shop this weekend, ask them how to solve the problem(106 too short, 108 too long), not about the KMC, the KMC is history.
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Old 04-20-12, 03:04 AM
  #105  
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Originally Posted by Psimet2001 View Post
Wow. You completely disagree with us.

You realize Papa Ado works for KMC right?

I avoided the chain length discussion earlier, but those pictures you posted - that chain is WAY short. Period. If you disagree - you are simply wrong.
It is not that I don't agree with your guys, the bike shifts smooth with 106 links on the stand and on the road with my 185lb body, on and off to the 28t no problem what's so ever. 108 links, chain rubbed the derailleur pulley when in small - small combo.
I don't know what to say, I will ask some pro mechanics this weekend.
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Old 04-20-12, 03:47 AM
  #106  
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Originally Posted by RTDub View Post
This thread has a life of its own.

Here's my big/big. Not a KMC, but this is how I make all of my bikes look while doing the cross-chain check. OP, I think your chain is sort :shrug:

yours is a long cage, it is a different story.
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Old 04-20-12, 03:52 AM
  #107  
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My Sram PPC-1090 chain, 106 links with a powerlink, it also shifts fine.

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Old 04-20-12, 05:30 AM
  #108  
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Originally Posted by coolmingli View Post
yours is a long cage, it is a similar story.
ffa

Mid cage. My point was that anything that looks like the short cages in this thread are woefully short, as others have agreed.
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Old 04-20-12, 07:43 AM
  #109  
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Originally Posted by coolmingli View Post
My Sram PPC-1090 chain, 106 links with a powerlink, it also shifts fine.

TOO. SHORT.

This is how to kill a der.
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Old 04-20-12, 10:00 AM
  #110  
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Uh oh, I agree with Bob
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Old 04-20-12, 12:14 PM
  #111  
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Originally Posted by RTDub View Post
Uh oh, I agree with Bob
Such is the burden of the know-it-all. Everyone will be in agreement with you at some point.
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Old 04-20-12, 01:27 PM
  #112  
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Originally Posted by RTDub View Post
This thread has a life of its own.

Here's my big/big. Not a KMC, but this is how I make all of my bikes look while doing the cross-chain check. OP, I think your chain is sort :shrug:

What method did you use to size your chain? Big-big+1, or something else?
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Old 04-20-12, 02:03 PM
  #113  
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Originally Posted by ThermionicScott View Post
What method did you use to size your chain? Big-big+1, or something else?
Big/Big outside of RD +1 link. This is a 50/34 with a 12-25 cassette on a cross frame and a mid-cage Sora RD. Regardless of cage size, my personal preference is to have the chain as vertical as possible between the jockeys when on big/big, threaded through the RD.

As always, thank you Sheldon Brown.

I bet the Mechanics forum would have something worthwhile to say about this.
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Old 04-20-12, 09:26 PM
  #114  
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I went to Performance today, didn't bring my bicycle, I took 2 photos of the bikes on display, chain length seems similar to mine.
Both bikes with compact front, the 105 is on 11-28 cassette, the Sora is on 12-25 Cassette.



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Old 04-21-12, 02:55 AM
  #115  
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^^^ Too. Short.

To date:

1. Every other poster has suggested: Too short.

2. A guy from the KMC factory suggested: Too short

3. Shimano tech docs suggest: Too Short

A quick gear inch calculation shows difference between your compact set-up and a standard 53/39 11-25 is only two inches in terms of the diffence between the highest and lowest gear inches in each range.

Also, a quick look at the tech docs shows that a DA SS rer der has a max tooth cpacity of 28 and a total cpacity of 33T. You are at the very limit of capacity for your rear der but within spec.
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Old 04-21-12, 06:54 AM
  #116  
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Originally Posted by coolmingli View Post
I don't know what to say, I will ask some pro mechanics this weekend.
You already did....and we told you - you're doing it wrong.
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Old 04-21-12, 08:45 AM
  #117  
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Originally Posted by Psimet2001 View Post
You already did....and we told you - you're doing it wrong.
Maybe I should get a chain tensioner?
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Old 04-21-12, 09:03 AM
  #118  
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Originally Posted by coolmingli View Post
Maybe I should get a chain tensioner?
OTOH, you can go out and enjoy the bike and not worry about what people on the 41 think about your chain length. If it works fine, then do you really care?
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Old 04-21-12, 09:43 AM
  #119  
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Originally Posted by coolmingli View Post
My Sram PPC-1090 chain, 106 links with a powerlink, it also shifts fine.

This^^^ is embarrassingly too short.
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Old 04-21-12, 09:48 AM
  #120  
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Again with the chain length discussion - guys....drop the "big-big+" crap. It was a great technique back in the day when odds are no one would ever change their gearing and the chain wrap was relatively reasonable.....or if you're pumping out bikes from a factory assembly operation.

If you're in the real world and it's your big.....small-small...and just take out enough links for it to be slightly under tension - not rubbing on the rd cage. Then run whatever the hell you want if the chain isn't long enough then you an not physically run that gearing on the bike as any longer chain won't work on that crank cassette combo.
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Old 04-21-12, 09:50 AM
  #121  
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Originally Posted by coolmingli View Post
My Sram PPC-1090 chain, 106 links with a powerlink, it also shifts fine.

Oh and ditch the crappy gore cables. The Teflon coating in the inners flakes off and jambs the housings up causing, of all things, drag. You can see it flaking on your inner between the pinch bolt and the cable end.
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